FIG. 12 is a cross-sectional view showing an on-off valve 1 according to a first prior art. The on-off valve 1 includes a valve body 3 axially displaceably held within a housing 2, and a spring member 4 fitted over the valve body 3 for exerting a spring force on a flange portion of the valve body 3 in first (one) axial direction x1. The housing 2 is formed with a supply port 5 and an outlet port 6, and a valve seat 7 is formed to circumscribe the supply port 5. The valve body 3 closes a valve path when a contact portion thereof is pressed on the valve seat 7 and opens the valve path when the contact portion moves away from the valve seat 7. The contact portion of the valve body 3 is formed with a seat portion 8 comprising rubber or resin for preventing the contact portion and the valve seat 7 from forming a clearance therebetween during valve closure so as to ensure reliable closure of the valve path. When the valve body 3 is thus pressed (seated) on the valve seat 7, the interior of the housing 2 is partitioned into a first pressure chamber continuous with the supply port 5 and a second pressure chamber continuous with the outlet port 6. The on-off valve 1 is also provided with a solenoid 10 in the housing 2 for exerting an electromagnetic force on the valve body 3 comprising a ferromagnetic material in a second (opposite) axial direction x2, thereby on-off controlling fluid communication between the supply port 5 and the outlet port 6 cooperatively with the spring member 4.
When the solenoid 10 is off, the valve body 3 is applied with the spring force working in the axial direction x1 by the spring member 4 to assume a cutoff position where the seat portion 8 is pressed on the valve seat 7, thereby cutting off the fluid communication between the supply port 5 and the outlet port 6. When the solenoid 10 is on, the valve body 3 is applied with the electromagnetic force working in the second axial direction x2 by the solenoid 10 to assume a spaced position where the seat portion 8 is spaced apart from the valve sheet 7, thereby providing fluid communication between the supply port 5 and the outlet port 6. Thus, the fluid communication between the supply port 5 and the outlet port 6 can be switched on and off.
FIG. 13 is a cross-sectional view showing a pressure reducing valve 11 according to a second prior art. The pressure reducing valve 11 includes a valve body 15 held within a housing 14 defining therethrough a valve path connecting a primary port 12 and a secondary port 13. The valve body 15 regulates the opening of the valve path. The valve body 15 is linked to a diaphragm 16 held within the housing 14 via a valve shaft 17. The diaphragm 15 receives the pressure of fluid in a pressure chamber 18 held at a secondary pressure and applies the valve body 15 with a driving force working in such a direction as to close the valve path based on that pressure of fluid. The pressure reducing valve 11 is also provided with a pressure control spring 19 for applying the valve body 15 with a driving force working in such a direction as to open the valve path. Thus, the pressure reducing valve 11 is configured to adjust the secondary pressure to the pressure set by the pressure control spring 19.
The valve body 15 closes the valve path when the contact portion thereof is pressed on a valve seat 20 formed in the housing and opens the valve path when the contact portion moves away from the valve seat 20. The contact portion of the valve body 15 is formed with a seat portion 21 comprising rubber or resin for preventing the contact portion and the valve seat 20 from forming a clearance therebetween during valve closure so as to ensure reliable closure of the valve path.
FIG. 14 is a cross-sectional view showing a valve device 22 according to a third prior art. The valve device 22 includes an on-off valve 23 and a pressure reducing valve 24, which are formed integrally with a housing 25 defining a flow path so as to be located intermediately of the flow path through which fluid flows from the supply side down to the outlet side. The on-off valve 23 and the pressure reducing valve 24 include respective valve bodies 26 and 27, each of which closes the valve path when the contact portion thereof is pressed on a respective one of valve seat portions 28 and 29 formed in the housing 25 and opens the valve path when the contact portion moves away from a respective one of the valve seat portions 28 and 29. The contact portions of the respective valve bodies 26 and 27 are formed with respective seat portions 30 and 31 each comprising rubber or resin for preventing each of the contact portions and a respective one of the valve seat portions from forming a clearance therebetween during valve closure so as to ensure reliable closure of the valve path (see patent document 1 for example).
Patent document 1: Japanese Patent Laid-Open Publication No. 2003-49997 (p. 4-5, FIG. 3)